Welcome to HVAC-Talk.com, a non-DIY site and the ultimate Source for HVAC Information & Knowledge Sharing for the industry professional! Here you can join over 150,000 HVAC Professionals & enthusiasts from around the world discussing all things related to HVAC/R. You are currently viewing as a NON-REGISTERED guest which gives you limited access to view discussions

To gain full access to our forums you must register; for a free account. As a registered Guest you will be able to:

Participate in over 40 different forums and search/browse from nearly 3 million posts.

The first thing you need to understand is that a properly designed duct system is pretty well balanced. Couple that with the fact that a zone control system is designed to primarily control otherwise out of balance conditions and you can begin to get a handle on the need or lack thereof for a zone control system. An example of a well designed system that benefits from zone controls would be a system where there is one room with a lot of glass plus skylights. On a sunny day, that room may need 650 CFM to maintain proper indoor temperature. But at night and on cloudy days, it needs a lot less. So, while the rest of the house is well balance and comfortable, the sun room needs special attention to keep from over cooling at reduced load conditions.

Now down to the actual system. Fist and foremost, each zone must be capable of heating or cooling the room(s) it controls. I've seen systems where one zone is under served and calls constantly. This can lead to the rest of the house being cold with an Infinity system. So proper basic design is a must!

Furthermore, any zone within the design should be capable of handling at a minimum, 25% of the minimum airflow. This often times means multiple rooms should be zoned as a group and it also means the supply outlets should normally be about 30% larger than would otherwise be used.

The zone logic for the Infinity system is that there is no by-pass damper for excess static relief but rather the user interface and zone interface together calculate the relief strategy on a moment-to-moment basis. What this means is that each day the system 'samples' the airflow through each zone and determines how much air it can handle. This is witnessed by a high airflow noise each day at about 1pm (factory default time but can be changed if desired) through each zone supply outlet for about 1-minute. That airflow is then used for the next 24-hours to regulate the dampers. When any zone calls, the controls determine what the last sampled airflow as for that zone and if it can't handle all the airflow needed, another zone damper or multiple dampers are partially opened sufficiently to relieve the excess static. Which damper(s) are opened partially or fully is totally dependent on the temperature in each zone in reference to the set-point, the trend in each zone relative to the set-point, the time since the last call for treatment in each zone and how long historically it's been between calls for treatment in each zone. No point trying to outsmart the system, it's calculating from all the variables the logic for operation.

Here is where an improper design can run amok. If you have a zone that can't satisfy due to under sizing for any reason, the logic will be to open other dampers to relieve the high static in that one zone. But if that zone, when wide open, cannot satisfy ever, then it keeps calling and the other zones keep relieving, giving you a totally out of balance situation and discomfort. I've repaired several system with Infinity/Evolution dampers and found all sorts of attempted remedies, including by-pass dampers (forbidden on Infinity/Evolution systems), 45° dampers instead of the normal 90° dampers, under sized dampers that allow constant airflow by-pass, all a result of poor original system design.

Be aware that there are many company's out there that will purport to do zone design. The ones who can really deliver are few and far between despite the hyperbole. Shop carefully. Do not accept any company that can't present you with the data to support their design, before any work is done. You're looking for a proper load analysis by Manual J-8 standards, a proper duct design using both Manuals D + Z and supply/return terminations using Manual T. Of course, Manual S should be used for equipment selection. I'd highly recommend design static be no more than .2, though .3 to .35 will most likely be closer to the end result.

If YOU want change, YOU have to first change.

If you are waiting for the 'other guy' to change first, just remember, you're the 'other guy's' other guy. To continue to expect real change when you keep acting the same way as always, is folly. Won't happen. Real change will only happen when a majority of the people change the way they vote!

It has been awhile seen I have sold Carrier (I'm not in the business any longer) but the Infinity control will operate all the add-ons.

The only problem with a small zone is the other dampers will open as opposed to having a by-pass damper. No harm done. But I would oversize the ductwork to the smaller areas so the other dampers do not need to open as much and over condition those areas.

+1 wth zoning or most system, he supply ductwork probably can't be too big...within reason. The above is also why you want the system properly sized or even slightly undersized. In the great white north, it's very easy to oversize. Desing termpatures are often not as warm or cold as people in those areas think they are.

For ventilation. What you can do is use an independant ventilation controller, and command the Infinity to run the fan using the "G" terminal. IF you're going ot do that, I'd also recommend looking beyong this "30 min/hr" requirements and get a on demand ventilation system that measures CO2 levels instead. 50% ventilation will over ventilate most of the time some tiems and underventilate other times. Ventilation requirments will vary based on outdoor temperature and wind conditions.

The zone logic for the Infinity system is that there is no by-pass damper for excess static relief but rather the user interface and zone interface together calculate the relief strategy on a moment-to-moment basis. What this means is that each day the system 'samples' the airflow through each zone and determines how much air it can handle. This is witnessed by a high airflow noise each day at about 1pm (factory default time but can be changed if desired) through each zone supply outlet for about 1-minute. That airflow is then used for the next 24-hours to regulate the dampers. When any zone calls, the controls determine what the last sampled airflow as for that zone and if it can't handle all the airflow needed, another zone damper or multiple dampers are partially opened sufficiently to relieve the excess static. Which damper(s) are opened partially or fully is totally dependent on the temperature in each zone in reference to the set-point, the trend in each zone relative to the set-point, the time since the last call for treatment in each zone and how long historically it's been between calls for treatment in each zone. No point trying to outsmart the system, it's calculating from all the variables the logic for operation.

I'm spec'ing the infinity because it is what I believe (after shifting through many of this forums threads) to be the best zoning system. I currently have an SLP98V with iComfort wi-fi control, and while the system is great, the harmony iii zoning system leaves a lot to be desired from my research. If you think there is a better zoning system out there let me know. I want to have the "best" system available.

Originally Posted by skippedover

are many company's out there that will purport to do zone design. The ones who can really deliver are few and far between despite the hyperbole. Shop carefully. Do not accept any company that can't present you with the data to support their design, before any work is done. You're looking for a proper load analysis by Manual J-8 standards, a proper duct design using both Manuals D + Z and supply/return terminations using Manual T. Of course, Manual S should be used for equipment selection. I'd highly recommend design static be no more than .2, though .3 to .35 will most likely be closer to the end result.

I can't agree with you more. I wish some of the pro's like yourself and George2 were in my city, because it seems like help is very difficult to find here.

For ventilation. What you can do is use an independant ventilation controller, and command the Infinity to run the fan using the "G" terminal. IF you're going ot do that, I'd also recommend looking beyong this "30 min/hr" requirements and get a on demand ventilation system that measures CO2 levels instead. 50% ventilation will over ventilate most of the time some tiems and underventilate other times. Ventilation requirments will vary based on outdoor temperature and wind conditions.

If I use an independent ventilation controller and command it to run the infinity system by the G terminal, if the infinity system is off, won't all the zone dampers also be in the "closed" position (therefore, no ventilation will take place since the fan is running but no zones are open)?

IF there is a call for "fan" operation and no call for heating or cooling the dampers should all open to curculate air.

Teddybear, and a few others would be better people to ask about ventilation control. Since you're in a climate where much of the year has minimal cooling loads, if you have a tight home that needs ventilation, a ventilating dehumidifier might be the best option. ERV's/HRV's often have a good 10 year payback when you look at their delivered efficeincy and the installed cost compared to how much energy they actually save. Plus slightly pressurizing a building as well has advantages as well over balanced air exchange. Most all commerical buildings are kept slightly pressurized.

Troll through Skips posts, definitely help you get a better picture of communicating zoning. Also, heed his suggestion that zoning may be overkill unless you have a unique, variable load situation.

If the house is crappy/sick, fix the house if you can instead of attempting to treat the symptoms with zoning. (in "new house" situation, avoid crappy/sick at design step)

I believe the American Standard/Trane system does all the great stuff infinity does plus the comm stat does a LOT more. Door locks, lights, video all wifi. Same system time Warner charges $35 a month for.

Also, it measures static pressure rather than calculating it based upon amp draw at rpm. Not sure if this is better, worse, or what. Maybe just different. Hopefully this will elicit more knowledgable comments as I would like to better understand how these two awesome systems compare.